Improvement in knob-latches



H. n. E-LWELLam; TAYLOR.'

KNOB-LATCH.

Emma Feb. 23,1976.Vv

4 v N. PETERS. PHOTO-LITHOGRPIIEH. WASHILIGTON. D C.

" UNITED STATES HENRY H. ELwELL AND THOMAs TAYLOR, OE NORWALK, CONNECTICUT, y j

APATENT ASSIGNORS TO THE NORWALK LOCK COMPANY, OFT-SAME PLAGE.

IMPROVEMEN'I-'IN KNOB-LATCHES. l v fe Specification forming part of Letters Patent No. 173,2 [7, dated February .8, 1876; application filed January 17, 1876. 'I Y i To all whom it may concern:

Be it known that we, HENRY H. ELwELLv and THOMAS TAYLOR, both of Norwalk,lin,v

the county of Fairfield and State of Connectr, cut, have invented a newV Improvement in Knob-Latches; and,wev do herebydeclare the following, when taken inconnection with the accompanying drawings, and-the letters of in a state'of rest; Fig. v2, an interior view,

the parts occupying the position as when the bolt is forced back asin the act of closing the door. f

This invention relates to an improvement in what are commonly called f knob-latches,77

the object of the invention beingto adapt a single spring, so that it may be strong on the knob, but light on the bolt, in order that the resistance may be less on the bolt in closing the door than when the spring is alike on both knob and bolt, the force to return the knob being much greater 'rhanthat necessary for throwing the bolt 5 hence, when the s ame force is applied to both the resistanceoffered by the bolt in closing is much greater than necessary for the operation of the bolt; and the inventionconsists. in abell-crank lever hung in'a case at the angle', one arm worked by the hub, theother attached tothe bolt, so that turning the knob the lever willbe turned, and the bolt drawn or thrown accordingly, combined with a second lever, the longer arm of which bears upon the arms of the, hub; and between the shorter arm of the second lever and a point nearthe fulcrum of the other lever, a spring is arranged, the tendency of which is to` force both levers against the arms of the hub upon Opposite sides, and so that in turning the hub the spring exerts its force upon the hub through both levers, and so that when the bolt is forced in without turning the knob the' principal lever only is turned, and theresistance of the spring to such turn- .ing much less than the resistance to the movement of the combined levers, as more fully hereinafter described. y

a is the hub, provided-with the arms b c, and arranged in the case inthe usual mani ner. A is one-arm, and B the other-arm, of a bell-crank lever, having its fulcrum at d'witlr-V in the case, the arm A extendingaroundl the hub, so that either arm of the hub will bear 'upon acorresponding partof the armA accordingly as the knob is4 turned, and to the arm B the latch-bolt C is attached, also in 'the usual manner; hence vby vturning ythe knob in either direction the latch-bolt will be' drawn.

D is a second lever, having its fulcrum at c,

one arm extending to the hub'an d so as .to'

bear upon. the 'arms of the hub opposite the arm A of the principal lever. Onv the other arin of the lever D is a spring-seat, f, and'at a point on the leyer B, forward ofthe fulcruni, is a similar seat, n. Between these two seats, f and n, a bent or other suitable spring,

E, is arranged, one endin each seat, the tendency of which is to force the arms of there- 'spective levers upon vthe hub; hence, in turning `-the hub, vthe power ofv the spring upon both arms is exerted upon the hub to cause it to return to its place of rest when free.

The principal lever being'independent of' the lever'D the bolt maybe forced inward, as seen in Fig. 2, without in any way affecting the hub or lever D, and theonly' resistance offered to this forcing in of the bolt isl the bearing n upon the spring, and this is so near the fulcrum as to be very light, yet suiiicient to force the bolt outwardwhen free, the po wer l of the spring through the leverv D being pref-y erably considerably greater than that through the principal lever. v

The power of the spring may be increased by forming several seats at u on the principal lever at varying distances vfrom the fulcruni, it being' understood that the farther the bearing is from the fulcruin the greater the power l of the spring upon the lever. 'v This inventionv is applicable to all classes of knob-latches.

We claim- I The combination in a knob-latch, of the hub, the principal lever A B, the bolt hung to one arm of the lever, the auxiliary lever D, and

the spring E, substantially as described.

HENRY H. ELwELL. THOMAS TAYLOR.

Witnesses: l I

` v C. M'. LAWRENCE,

WILLIAM T. BOUTON. 

